Gorthorog
Recognizing the power of the Witch-king and of his master in Mordor, these creatures willingly joined with Angmar and Sauron. The smiths of Angmar outfitted them with powerful arms and armor, and they became Angmar’s most devastating fighters, set at the front of Angmar’s armies like the sharp edge of a blade. With their help, the Witch-king won many battles against the kingdoms of Arnor. Some say that it was Gorthorogs who tore down the Tower of Amon Sûl, toppling it into ruin, but none survive to confirm that tale.
In the last battle to drive Angmar out of the lands of Arnor, the enemy made one grave error. The Witch-king had held his last few Gorthorogs in Carn Dûm, planning to lure his enemies to their ruin with a false retreat. But in the end his attempt to reach the fortress failed, and the Witch-king was driven from the North. Angmar was defeated.
With Angmar’s forces scattered, the Gorthorogs retreated to the dark places of that fallen kingdom, which were to them much like the cracks and shadows in the North where they once dwelt. Some also say that a few Gorthorogs fled south and east, all the way to Mordor, and there were bred with Trolls by Sauron, and thus had a part in the creation of the Mordor’s most powerful and darkest of creatures. Of this, not even the Wise can say for certain.
Now, with the rumors of a flame rekindled in Angmar, there remains the danger that these creatures might yet ally themselves with whatever evil returns to that barren realm.